1. Field of the Invention
The present invention relates to a connector for attaching two metal piece parts together and, more particularly, to a bolt connector with an integral burr configuration that provides for improved stiffness in the connection.
2. Description of the Prior Art
There are many well-known arrangements for attaching together metal sheets or a metallic framework structure. A relatively stiff and strong connection can be made by welding the piece parts together. In many instances, however, a weld is not appropriate. For example, when constructing a metal enclosure or rack structure, the arrangement must be capable of being dis-assembled and reconfigured (e.g., enlarged, lengthened, moved, etc.). In these instances, the metal piece parts must be bolted together.
There are a countless number of methods for bolting together metal assemblies which, after assembly, prevent relative movement between the bolted pieces. For example, this may be accomplished by restricting the size of the bolt holes in the members to be joined. In fact, in some instances, the bolt must actually be driven forcibly through the holes which offer no clearance over the basic bolt diameter, thereby resulting in an interference fit. It has been found that such an arrangement is successful if the bolt is a machined bolt, i.e., if the diameter over the threads is the same as the diameter of the shank of the bolt. However, in the case of bolts whose threads are rolled, the diameter over the threads is larger than the shank diameter. Consequently, when the holes in the members to be joined are sized to provide no clearance over the threads, there will be a resultant clearance with respect to the shank, since its diameter is smaller. Therefore, after the members have been joined, the interference fit that would otherwise prevent movement will be lost.
One solution to this problem is disclosed in U.S. Pat. No. 4,427,318 issued to E. G. Kaminski on Jan. 24, 1984. The '318 patent discloses a joint connection where one of the members is provided with a hollow deformable boss having inwardly sloping sidewalls which are configured to slip-fit partially within a cooperating aperture in the other member. The members are joined by a nut and bolt such that the boss moves outwardly and makes metal-to-metal contact with the other member and with the shank of the bolt. When the nut and bolt are released, the boss will relax into its original position. However, repeated use of the boss (that is, movement followed by relaxation) may eventually result in fatigue failure, shearing the boss from the metal member.